ABSTRACT
OBJECTIVE: To assess the influence of soil on the effectiveness of two new slow-release formulations (floating and non-floating) of pyriproxyfen coextruded with low-density polyethylene. METHODS: Two slow-release devices were developed using low-density polyethylene, pyriproxyfen as larvicide and calcium carbonate as filler. A factorial design was used to evaluate the effect of soil presence on the performance of each device. Weekly bioassays were performed. RESULTS: Soil presence affected treatment effectiveness, but this effect was associated with device type. The tablets were effective for nearly 3 months. CONCLUSION: Treatment effectiveness could be reduced because of the loss of pyriproxyfen by several physico-chemical processes such as adsorption into the soil.
OBJECTIF: Evaluer l'influence de la terre sur l'efficacité de deux nouvelles formulations à libération lente (flottante et non flottante) de pyriproxyfène coextrudé avec du polyéthylène de faible densité. MÉTHODES: Deux dispositifs à libération lente ont été développés en utilisant du polyéthylène de faible densité, du pyriproxyfène comme larvicide et du carbonate de calcium comme agent de charge. Un plan factoriel a été utilisé pour évaluer l'effet de la présence de terre sur les performances de chaque dispositif. Des essais biologiques hebdomadaires ont été effectués. RÉSULTATS: La présence de terre a affecté l'efficacité du traitement, mais cet effet était associé au type de dispositif. Les comprimés ont été efficaces pendant près de 3 mois. CONCLUSION: L'efficacité du traitement pourrait être réduite en raison de la perte du pyriproxyfène par plusieurs processus physicochimiques tels que l'adsorption sur la terre.
Subject(s)
Aedes , Insecticides/pharmacology , Pyridines/pharmacology , Soil/parasitology , Animals , Argentina , Biological Assay , Larva/drug effects , Mosquito Control , Polyethylene/pharmacologyABSTRACT
Antimicrobial wheat gluten film was obtained at pilot scale by Lactobacillus curvatus CRL705 bacteriocins inclusion in the film-forming solution. Bacteriocins' minimum inhibitory concentration for the film activation was 2133 AU cm(-3) (lactocin AL705) and 267 AU cm(-3) (lactocin 705). Mechanical and barrier properties as well as film ageing kinetics were not significantly affected by the addition of bacteriocins. The antimicrobial film performance during ageing was assessed. Film activity against Listeria innocua 7 and Lactobacillus plantarum CRL691 was observed over 50 days of ageing. Even when the release of bacteriocins from the film upon water contact was observed for both bacteriocins at the beginning of the ageing period, and anti-Listeria activity was delivered to the simulant up to the 15th day of ageing, film residual activity for both bacteriocins was observed over 50 days. The results confirm the potential of a gluten film doped with L. curvatus CRL705 bacteriocins as a carrier of bacteriocins to avoid Listeria and lactic acid bacterial growth, thus enhancing quality and safety in foods.
Subject(s)
Bacteriocins/metabolism , Food Microbiology , Glutens/metabolism , Lactobacillus/metabolism , Triticum/metabolism , Triticum/microbiology , Animals , Anti-Bacterial Agents/metabolism , Anti-Bacterial Agents/pharmacology , Bacteriocins/pharmacology , Food Contamination/prevention & control , Food Packaging , Food Preservation , Food Safety , Humans , Lactobacillus plantarum/drug effects , Listeria/drug effects , Meat/microbiology , Microbial Sensitivity Tests , Pilot Projects , Time FactorsABSTRACT
BACKGROUND: Bacteriocins produced by lactic acid bacteria offer enormous promise for food safety preservation. In this study an active multilayer film obtained by the incorporation of lactocin 705 and lactocin AL705, two bacteriocins produced by Lactobacillus curvatus CRL705 with antimicrobial activity against Lactobacillus plantarum CRL691 and Listeria innocua 7, respectively, was characterized for its potential application in active packaging technology. Film activity performance at different storage conditions, bacteriocins transfer into water and sunflower oil, and film surface properties were evaluated. RESULTS: Film activity against L. innocua 7 was maintained during 2, 4 and 6 weeks at 30, 10 and 5 °C respectively. At 30 and 10 °C, activity loss against L. plantarum CRL691 was observed on the second week of storage and after the fourth week at 5 °C. Results showed no significant difference for active multilayer film contact angle and seal properties compared to the control (without bacteriocins). A decrease in lactocin 705 inhibitory activity after sunflower oil contact was observed, while lactocin AL705 remained unaffected. After water contact, film activity was retained for both bacteriocins. CONCLUSIONS: As demonstrated by antimicrobial activity and physico-mechanical properties retention, lactocin 705 and AL705 active multilayer film present potential for application in active packaging technology.
